This option is relevant for viewing 3D objects. Wireframe mode means that you can see only edges of the object, while its shells remain transparent. Shading mode means that the shells are filled with color.
To change the display mode right-click on this geometrical object in the viewer and from the pop-up menu select Display mode --> Wireframe or Shading.
TUI Command: gg.setDisplayMode(ID, Short)
Examples:
Wireframe
Shading
Our TUI Scripts provide you with useful examples of Changing Display Parameters.